1. Warm Up Lesson Presentation Problem of the Day Lesson Quizzes

2. Warm Up Use a calculator to find each value. Round to the nearest hundredth. 1. 2. 3. 4. 5.48 3.74 7.42 6.93

3. Problem of the Day A side of a square A is 5 times the length of a side of square B . How many times as great is the area of square A than the area of square B ? 25

4. Learn to use the Pythagorean Theorem and its converse to solve problems. The Pythagorean Theorem

5. Pythagorean Theorem leg hypotenuse Vocabulary

6. Pythagoras was born on the Aegean island of Samos. He is best known for the Pythagorean Theorem , which relates the side lengths of a right triangle.

8. 4 5 c 6.40  c Pythagorean Theorem Substitute for a and b. a 2 + b 2 = c 2 4 2 + 5 2 = c 2 16 + 25 = c 2 Simplify powers. Additional Example 1A: Finding the Length of a Hypotenuse Find the length of the hypotenuse to the nearest hundredth. 41 = c 2 41 = c Solve for c; c = c 2 .

9. When using the Pythagorean Theorem to find length, use only the principal square root. Helpful Hint

10. 15 = c Pythagorean Theorem Substitute for a and b. a 2 + b 2 = c 2 9 2 + 12 2 = c 2 81 + 144 = c 2 Simplify powers. Additional Example 1B: Finding the Length of a Hypotenuse Find the length of the hypotenuse to the nearest hundredth. triangle with coordinates (1, –2), (1, 7), and (13, –2)‏ 225 = c Solve for c; c = c 2 .

11. Check It Out: Example 1A 8.60  c Pythagorean Theorem Substitute for a and b. a 2 + b 2 = c 2 5 2 + 7 2 = c 2 25 + 49 = c 2 Simplify powers. Find the length of the hypotenuse to the nearest hundredth. 5 7 c 74 = c Solve for c; c = c 2 .

12. triangle with coordinates (–2, –2), (–2, 4), and (3, –2)‏ The points form a right triangle. (–2, –2)‏ (–2, 4)‏ (3, –2)‏ Check It Out: Example 1B 7.81  c Pythagorean Theorem a 2 + b 2 = c 2 6 2 + 5 2 = c 2 36 + 25 = c 2 Simplify powers. Substitute for a and b. Find the length of the hypotenuse to the nearest hundredth. x y 61 = c Solve for c; c = c 2 .

13. Additional Example 2: Finding the Length of a Leg in a Right Triangle 25 7 b Find the positive square root. b = 24 a 2 + b 2 = c 2 7 2 + b 2 = 25 2 49 + b 2 = 625 – 49 –49 b 2 = 576 Solve for the unknown side in the right triangle to the nearest tenth. Pythagorean Theorem Substitute for a and c. Simplify powers. Subtract 49 from each side.

14. Check It Out: Example 2 b  11.31 12 4 b a 2 + b 2 = c 2 4 2 + b 2 = 12 2 16 + b 2 = 144 – 16 –16 b 2 = 128 Find the positive square root. Solve for the unknown side in the right triangle to the nearest tenth. Pythagorean Theorem Substitute for a and c. Simplify powers. Subtract 16 from both sides.

15. Additional Example 3: Using the Pythagorean Theorem for Measurement a 2 + b 2 = c 2 350 2 + 725 2 = c 2 122,500 + 525,625 = c 2 648,125 = c 2 805 ≈ c Find the positive square root. Substitute for a and b. Pythagorean Theorem The two planes are approximately 805 miles apart. Two airplanes leave the same airport at the same time. The first plane flies to a landing strip 350 miles south, while the other plane flies to an airport 725 miles west. How far apart are the two planes after they land? Simplify powers. Add.

16. Check It Out: Example 3 a 2 + b 2 = c 2 11 2 + 7 2 = c 2 121 + 49 = c 2 170 = c 2 13 ≈ c Find the positive square root. Substitute for a and b. Pythagorean Theorem The two birds are approximately 13 miles apart. Two birds leave the same spot at the same time. The first bird flies to his nest 11 miles south, while the other bird flies to his nest 7 miles west. How far apart are the two birds after they reach their nests? Simplify powers. Add.

17. Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems

18. Lesson Quiz 1. Find the height h of the triangle. 2. Find the length of side c to the nearest meter. 3. An escalator is 32 ft tall and 40 ft from a wall. What distance does the escalator carry shoppers? 8 m 12 m h c 10 m 6 m 9 m Use the figure for Problems 1 and 2. 2624 ≈ 51 ft

19. 1. Identify the height of the triangle. A. 14 m B. 15 m C. 16 m D. 17 m Lesson Quiz for Student Response Systems

20. 2. Identify the length of side c to the nearest meter. A. 9 m B. 10 m C. 11 m D. 12 m Lesson Quiz for Student Response Systems

21. 3. The height of a tower is 30 ft. It casts a shadow of 36 ft on the ground. What is the distance between the tip of the tower to the corresponding tip of its shadow? A. B. C. D. Lesson Quiz for Student Response Systems